Vibrating dental tools and, in particular, ultrasonic dental tools are known.
U.S. Pat. No. 5,320,532 (Farzin-Nia et al.) teaches an ultrasonic tool for fracturing the interface between dental structures and, specifically, for the removal of orthodontic bands or brackets from teeth after the completion of treatment. The working tip of the tool may be wedge-shaped, flat or needle shaped. In one embodiment, a pair of spaced projections are disposed on either side of an engaging surface to provided a receiving area for the bracket to minimize slipping off. In use, the tip of the tool is placed against a bracket and ultrasonic energy is transferred through the bracket to the adhesive layer.
U.S. Pat. No. 5,733,119 (Carr) teaches a microsurgical drill bit, which can be connected to an ultrasonic transducer. The drilling tips are angled and may have bent end portions to permit the tool to be held at a comfortable angle.
While drilling devices and simple devices for the removal of adhesively connected dental structures are known, there is a need for a dental tool adapted for the removal of crowns and bridges.
The crowning and bridging of teeth is a common practice in dentistry. There are a number of indications for crowns and bridges. Some of the more common indications are: heavily restored teeth with little of the original teeth left; following root canal treatments; and bridges for the replacement of missing teeth. Crowns and bridges may also be used for aesthetic reasons.
When a tooth is prepared for a crown, the practitioner removes or shaves off the surface of the tooth to a depth of approximately 1.5 millimeter (mm). The practitioner generally then cements a temporary crown to the tooth. The practitioner then generally awaits lab work on the tooth, before cementing in a permanent crown.
There are many instances where a practitioner must remove a crown or bridge. One common instance is the removal of a temporary crown. This may prove particularly challenging where the temporary crown fits tightly over the original tooth. Another common instance is the removal of a permanent crown that has been temporarily cemented. This might occur, for example, where the practitioner wishes to obtain approval of the crown from the patient before permanently securing it. This might also occur where the practitioner wishes to ensure that tooth sensitivity will subside before permanently securing a crown.
Other common instances may arise after a crown has been permanently secured. For example, removal of a crown is required where there is caries underneath it and the practitioner does not wish to cut the crown to provide treatment. Similarly, a crown may need to be removed where it is necessary to perform a root canal on the underlying tooth. Yet another instance might be where one crown of a bridge becomes loose and the practitioner must remove the other crowns of the bridge in order to re-cement the bridge.
Existing crown removal tools generally involve the application of a blunt force to the crown, which often results in broken or fractured crowns or teeth. This can add complexity and expense to a dental procedure and, in addition, may cause additional discomfort to a patient. The inventor is aware of an ultrasonic crown removal tool, the ATD Automatic Crown & Bridge Remover by J. Morita, USA, Inc. This tool consists of ultrasonic steel string arranged as a loop and a pneumatic hook that attaches to a hand piece that causes slow movement of the hook. The steel string, while designed to assist with separating the crown from the root, suffers from a number of drawbacks. The steel string is difficult to position if the teeth are close together. Further, if the crown-tooth interface is smooth, the string will not catch at this position. The string also has trouble penetrating the crown-tooth junction. Finally, due to the application of pressure on one side of the crown or tooth-crown junction, the crown almost invariably breaks during the removal procedure, which adds to the complexity and expense of the procedure.